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Paul

Model output discussion - here comes the beast!

Paul

Please only post model discussion in this thread 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

We also have a special post SSW cold spell discussion open here:
https://www.netweather.tv/forum/topic/89358-ssw-related-cold-spell-will-it-wont-it/

Thank you!

Message added by Paul

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4 minutes ago, BleakMidwinter said:

But quite a few people in here have made the point that this is highly likely to be powdery dry snow which is thought to approximate c.3cm snow to 1mm of precipitation, rather than the usual 1mm ppn=1cm snow

In which case, triple everything...?

I read that myself. I presume that being dry snow and falling on a dry cold surface there is no initial thaw/melt when settling on top.

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23 minutes ago, Man With Beard said:

Sorry I don't buy it. When I view charts like we've seen tonight when the temperature is just above the threshold for snow, I expect an inch of rain, not an inch equivalent of snow.

Which charts are those then with temps just above snow threshold etc where we could expect rain 

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ECM ensemble mean at T168.  This channel or Northern France feature seems likely, it's more a question of the track, fascinating model watching!

EDM1-168.GIF?23-0

And T240 mean looks interesting with the cold still firmly in place:

EDM1-240.GIF?23-0

Edited by Mike Poole

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47 minutes ago, kold weather said:

No its not, I've changed it to cms not inches onthe settings. So it IS 5-7cms in the south and 10-15cms in the SW. Nothing to sneeze at still but its not quite the snow disaster some thought.

 

Bite your hand off for a guaranteed 5cms of West Sussex snow if offered now. 

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2 minutes ago, Man With Beard said:

I don't know if perhaps this kind of micro-analysis of the snow potential needs moving into the dedicated cold spell thread ... but just thought I'd post the latest ARGEPE snow chart as to me it seems a reasonable idea of what to expect on the ground by Wednesday morning:

arpegeuk-45-114-0.png?23-17

Seems very plausible, I think depths will be deeper but those areas do seem the most likely places. Shower bands will track from NE to SW across the country, some will strike gold and others will be left dry but really cold. I reckon a few unexpected troughs will form at short notice and bury some places that are expecting little.

 

if I was a betting man I'd say a band through the Thames running SW over the South Downs and exiting between Portsmouth and Southampton 👍❄️

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Just now, ian33nw said:

Which charts are those then with temps just above snow threshold etc where we could expect rain 

I just mean when a low pressure just sits in the English Channel for 48 hours bringing up a southerly, I'd normally expect ridiculous amounts of rain on the south coast, even flooding amounts - whether the temperature is 3C or 30C! Better leave it there though, I see we've got a bit derailed by snow volumes tonight on here and I'm partly to blame...

Longer term - D8 onwards - one can see the complete mess the UK is in. No coherent direction at all. I imagine if it is very cold at D8, that cold may just sit and sit over the UK for quite a while, especially if there's snow cover (oh no I said it again!)

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1 minute ago, Man With Beard said:

I just mean when a low pressure just sits in the English Channel for 48 hours bringing up a southerly, I'd normally expect ridiculous amounts of rain on the south coast, even flooding amounts - whether the temperature is 3C or 30C! Better leave it there though, I see we've got a bit derailed by snow volumes tonight on here and I'm partly to blame...

Longer term - D8 onwards - one can see the complete mess the UK is in. No coherent direction at all. I imagine if it is very cold at D8, that cold may just sit and sit over the UK for quite a while, especially if there's snow cover (oh no I said it again!)

I get you now but some of the new members on here must wonder whats going on when people are saying inches of snow to come and you say inch of rain 

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4 minutes ago, Man With Beard said:

I just mean when a low pressure just sits in the English Channel for 48 hours bringing up a southerly, I'd normally expect ridiculous amounts of rain on the south coast, even flooding amounts - whether the temperature is 3C or 30C! Better leave it there though, I see we've got a bit derailed by snow volumes tonight on here and I'm partly to blame...

Longer term - D8 onwards - one can see the complete mess the UK is in. No coherent direction at all. I imagine if it is very cold at D8, that cold may just sit and sit over the UK for quite a while, especially if there's snow cover (oh no I said it again!)

Snow volumes are a valid discussion as its part of what is being modelled , I'm with you that sort of LP would deliver  a foot of snow IMBY at least

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6 minutes ago, Summer Sun said:

Blizzards and heavy snow from UKMO extended North Midlands south possibly the hot spots

ukm2.2018030212_168_lant.troplant_prp_fcst.gentracker.thumb.png.ddbb30e11af83cc9a632c26a6a55e59b.png

Not a million miles away from the GFS

Still T168 is a mile away in this situation. I wouldn't be entirely sure on the direction of this at T24!!

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18 minutes ago, Mike Poole said:

ECM ensemble mean at T168.  This channel or Northern France feature seems likely, it's more a question of the track, fascinating model watching!

EDM1-168.GIF?23-0

And T240 mean looks interesting with the cold still firmly in place:

EDM1-240.GIF?23-0

Yes good post- looks like another runner sliding across day 10-

Mike I think you should change your name to Cold !

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15 minutes ago, Summer Sun said:

Blizzards and heavy snow from UKMO extended North Midlands south possibly the hot spots

ukm2.2018030212_168_lant.troplant_prp_fcst.gentracker.thumb.png.ddbb30e11af83cc9a632c26a6a55e59b.png

Looks like UKMO as man with beard says takes more of the GFS approach (surely GFS can't be the leader in this)?, personally would like to see it flatter than that and a hundred or so miles further south to keep the cold locked in...but maybe that's more of me talking about my location.

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An IMBY post but this is pretty impressive from the ECM, Just gets to -8 at the end of the run.

graphe_ens3.php?mode=0&x=323&y=104&run=1

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Fantastic seeing these charts actually in range instead of in the joke range. Echos of Feb 1991

 

 

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what an ECM run!....Stunning is an overused word at times, but not this time.....T168 is snowmageddon............I just looked into the future and took this photo of my back garden this time next friday

download.thumb.png.cc658b3a81627e8d448ac7578fcfb5f0.png

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30 minutes ago, Summer Sun said:

Blizzards and heavy snow from UKMO extended North Midlands south possibly the hot spots

ukm2.2018030212_168_lant.troplant_prp_fcst.gentracker.thumb.png.ddbb30e11af83cc9a632c26a6a55e59b.png

If you follow back SW into the Atlantic there are 2 more potential LP 'runners' lining up.....interesting times indeed.

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13 minutes ago, AmershamMike said:

Tight - could you explain your fist line please? The rest I can just about figure out. Thanks! Bought my 6 and 2 year olds their first 🛷 today. Sure hope I haven’t jinxed anything!

Gfs- 4/ 24 hr..circular suites..ooz /6z/12z/18z.

The 18z is looked upon as a mish-mash of the medium sets..ie- ooz /12z..

However 18z is ref'ed as pub run..due to its bipolar dynamics!

This time in standing its on a level pegging; and being big brother again'st it bully-sister suites.

Ita a mixed-and usualy miss dynamical evolution of middle ground...then plot lost!!!..

But i'd advise due to time lapse/and situ atm...the 18z is actually laughably the form run.

And its evo's are likely more in%age..verifying.....

and after its nxt run..i'll elaborate further...for my points in note!

Edited by tight isobar

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1 hour ago, PerfectStorm said:

I don't often wish my life away (especially at weekends) but charts like this just make we wish I could skip the next few days!!

1ECM1-192.GIF?23-0

Have to say your avatar is very appropriate at this moment in time, as we could be heading straight into a Perfect 'winter' Storm! :cold::friends:

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Exceptionally snowy 12z GFS ensembles. Most runs keep any mild sector weak enough that the surface cold remains in place. That equals some huge falls for some.

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38 minutes ago, Froze were the Days said:

Looks like UKMO as man with beard says takes more of the GFS approach (surely GFS can't be the leader in this)?, personally would like to see it flatter than that and a hundred or so miles further south to keep the cold locked in...but maybe that's more of me talking about my location.

The GEFS / EPS are not suggesting this and a minute adjustment at this range can make a huge difference 'on the ground' for our tiny island! :)

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